This invention relates to an apparatus for providing and sensing coded information, and more particularly to a system including a composite card adapted to carry a binary code and an electronic card reader for receiving the card and detecting the code.
This invention has particular application to use in buildings, such as hotels, having large numbers of rooms required to be locked, and is intended to replace the conventional mechanical lock and key system now in general use. Although this invention will be described in connection with such use, it will be understood that the apparatus of this invention may be used with many card systems requiring coded information to operate the system.
Typical coded card and card reader systems presently employ a variety of encoded cards, such as punched cards, concealed magnetic strips, visible magnetic ink, reflecting material, and the like. The readers for sensing the codes carried by such cards include optical scanners, capacitance switches, magnetic detectors, mechanical switches, and the like. However, such systems are relatively complex, expensive, often overly sensitive, and require considerable maintenance. For example, optical readers are very costly and have high maintenance requirements. Capacitance and magnetic ink readers are also quite expensive. Magnetic strips typically cannot contain large amounts of data. Other readers are quite bulky and slow, and frequently have large power requirements. In addition, the less expensive cards have generally been constructed in a manner which allows their usefulness to be easily destroyed.
The apparatus of this invention provides a card and reader system which is compact, accurate and relatively inexpensive while at the same time having low maintenance and power requirements.